Boring head having extensible arm and relatively rotated concentric cutter



arch i4, 1%? J. KARLOVSKY, JR 3,309,144

BORING HEAD HAVING EXTENSIBLE ARM AND RELATIVELY RQTATED CONCENTRIC CUTTER Filed March 22, 1965 4 Sheets-Shed l arch 14, 1967 KARLOVSKY, JR

BORING HEAD HAVING EXTENSIBLE ARM AND RELATIVELY ROTATED CONCENTRIC CUTTER 4 Sheets-Sheet 2 Filed March 22, 1965 k i m d E Wm 0 M T 4. .8 f P March 14, 1 7 J. KARLOVSKY, JR

BORING HEAD HAVING EXTENSIBLE ARM AND I RELATIVELY ROTATED CONCENTRIC CUTTER 4 Sheets-Sheet 5 Filed March 22, 1965 r m a M my; E m5 0 a, w 7 W, Mi Q bx. mm J March 14, 1%?

J. KARLOVSKY, JR 3369 144 BORING HEAD HAVING EXTENSIBLE ARM AND RELATIVELY ROTATED CONCENTRIG CUTTER 4 Sheets-Sheet 4 Filed March 22, 1965 INVENTOR. Jew/qr A/HRLOVJK r; J?

United States Patent 3,309,144 BORING HEAD HAVING EXTENSIBLE ARM AND RELATIVELY ROTATED CONCEN- TRIC CUTTER Jerry Karlovsky, Jr., Nashville, Ill., assignor to National Mine Service Company, Pittsburgh, Pa., a corporation of West Virginia Filed Mar. 22, 1965, Ser. No. 441,458 7 Claims. (Cl. 299-60) This invention relates to a rotary boring head having Counter-rotating cutter elements and more particularly to a rotary boring head having a plurality of extensible radial arms with cutter elements extending forwardly therefrom and a central cutting element that rotates in a direction opposite to the radial arms and at a different angular velocity.

The multiple boring head continuous mining machine generally referred to as the McKinlay type mining machine has a plurality of boring heads extending forwardly therefrom with radially extending arms. The boring heads dislodge material from a vertical mine face and form a plurality of contiguous bores in the mine face. The boring heads each cut a plurality of circular kerfs about a common axis and wedge type breakers secured to the arms dislodge the annular cores of material remaining between the circular kerfs. The McKinlay type boring machine has many advantageous features. For example, the boring type mining machine forms elliptically shaped entries in the mine face that provide a certain amount of support for the roof portion of the entry or passageway. The boring type mining machine is considered a high capacity continuous miner capable of dislodging up to 10 tons per minute from the vertical mine face and is superior in many respects to other types of mining machines.

One of the principal limitations in the mining capacity of the boring machine is the velocity of the cutter elements located adjacent the axial center of the boring head. The cutting elements, due to their position adjacent the center of the boring head, have a reduced linear velocity when compared with the cutter elements extending forwardly from the ends of the radial arms. Where the boring head is formed as a single element, the angular velocity of the cutting elements adjacent the center of the boring head and the cutting elements adjacent the ends of the radial arms, is the same. There is, however, in unitary boring heads a substantial difference in the linear velocity of the cutter elements adjacent the center of the boring head and the cutter elements adjacent the ends of the radial arms. It has been determined that the boring head will operate more efiiciently where the cutter elements adjacent the center of the boring head and the cutter elements adjacent the ends of the radial arms are rotat ing at substantially the same linear velocity. Thus, by increasing the linear velocity of the cutter elements adjacent the center of the boring head, the efficiency and capacity of the multiple boring head continuous mining machine can be increased substantially.

In Us. Patent No. 3,069,147, entitled, Rotary Cutting Head, there is disclosed apparatus for rotating the center cutter portion of a rotary boring head at a different angular velocity than the cutter elements adjacent the ends of the radial arms. The boring head is constructed with two rotatable parts that rotate in the same direction at difierent angular velocities. The outer part has radial arms extending therefrom and the inner coaxial part has the center cutting portion extending forwardly therefrom.

In a boring type continuous mining machine having a pair of boring heads the direction of rotation of the boring heads is such that the material dislodged from the vertical face is directed toward the center of the mining 3L39l44 Patented Mar. 14, 1967 ice machine so that it can be conveyed rearwardly on the mining machine by the conveying mechanism provided therefor. The boring heads, therefore, rotate in opposite directions. When the boring machine having a pair of boring heads is utilized to widen an entry, considerable difficulty is encountered in maintaining the mining machine in a desired linear path paralleling the entry. To widen an entry, both boring heads are not simultaneously dislodging material from the face. For example, where the entry is being widened approximately one-half the width of the mining machine, the mining machine has one boring head that rotates freely in the existing entry while the other boring head is dislodging material from the face along a side wall of the existing entry. When both boring heads are active and are dislodging material from the vertical face, the counter rotation of the boring heads compensates for the turning torque created by the rotation of each boring head. When, however, only one boring head is dislodging material from a vertical face and the other boring head is rotating freely in an existing entry, the torque compensation of the counter rotating boring heads is not present. The mining machine tends, therefore, to follow a curved path in the direction of rotation of the active boring head that is dislodging the material from the vertical face. There is a need, therefore, for a multiple boring head type mining machine that can be utilized to widen existing entries and follow a relatively straight linear path as the entry is widened.

Briefly, the invention is directed to a continuous mining machine having a boring head with two portions rotatably relative to each other. The center portion is arranged to rotate in a direction opposite to the outer portion of the boring head that includes the radially extending arms. The center portion of the boring head is arranged to rotate at an angular velocity greater than the angular velocity of the radially extending arms. The apparatus for independently rotating the center portion of the boring head comprises a shaft connected to the center portion and extending rearwardly through a tubular passage in the boring head outer portion. The axial shaft and the outer portion of the boring head are rotatably relative to each other. The outer portion of the boring head has a rear- Wardly extending shaft that is tubular and has the center shaft coaxially positioned therein. The coaxial shafts extend inito the gear case positioned rearwardly of the bor ing heads and gearing is provided therein to rotate the axial shaft extending through the tubular shaft in a direction opposite to the direction of rotation of the tubular shaft. Wtih this arrangement the cutting elements on the radially extending arms are extensible and retractable Without interfering with the gearing for rotating the coaxial shafts.

In another embodiment of the invention the central portion of the boring head is provided with arm portions extending radially therefrom. The arms extending from the central portion of the boring head have cutting elements extending forwardly therefrom. The outer portion of the boring head has a plurality of radially extending arms that are extensible and may be retracted between the shorter radial arms extending from the boring head central portion.

Accordingly, the principal object of this invention is to provide a boring head for a continuous mining machine that has a central inner portion and an outer portion that are rotatably relative to each other in opposite directions.

Another object of this invention is to provide a boring head having relatively rotatable parts that are driven in opposite directions by gearing located in a gear case that is spaced rearwardly of the rotatable arms.

Another object of this invention is to provide a boring head for a mining machine wherein the central inner portion with arm members extending radially therefrom and an outer portion that has other arms extending radially therefrom.

These and other objects and advantages of this invention will be more completely disclosed and described in the following specification, the accompanying drawings and the appended claims.

In the drawings:

FIGURE 1 is a view in front elevation of a boring machne having boring heads with an inner portion that is rotatable relative to an outer portion.

FIGURE 2 is a view in section taken along the line 22 in FIGURE 1 illustrating the coaxial arrangement of the shafts that drive the relatively rotatable portions of the boring head.

FIGURE 3 is a schematic diagram in front elevation of the gear case housing the gears for rotating the coaxial shafts in opposite directions.

FIGURE 4 is a developed section in side elevation of the gearing for rotating the shafts in opposite directions.

FIGURE 5 is a schematic view in front elevation of a boring head having arm members that extend radially from the boring head central portion and the radial arms of the boring head outer portion retracted therebetween.

Referring to the drawings and particularly to FIG- URE 1, there is illustrated a boring type continuous mining machine generally designated by the numeral that has a frame member 12 with a centrally located, rearwardly extending conveyor mechanism 14. Secured to the frame 12 is a gear case 16 that encloses gearing for driving a pair of rotatable boring heads generally designated by the numerals 13 and 20. The gear case 16 is positioned rearwardly of the boring heads 18 and 20 and also includes gearing to drive a trimmer chain 22. The trimmer chain 22 is reeved about a plurality of sprockets 24 and has cutting elements thereon arranged to trim the roof and floor of the entry between the contiguous bores formed by the boring heads 18 and 20.

The boring heads 18 and 20 are of similar construction and each has :a tubular connecting shaft 26 (FIGURE 2) extending forwardly from the gear case 16. The tubular shaft 26 is suitably supported within the gear case and has a radially extending flange portion 28. The boring heads 18 and 20 each have a body portion 30 with a rear radially extending flange 32 that is secured to the flange 28 of shaft 26 by a plurality of bolts 34. The body portion 30 which may also be referred to .as the boring head outer portion, has a plurality, in this instance three, radially extending arms 36 that have sleeve members 38 positioned thereon. The radial arms 36 have an internal chamber or bore 40 in which there is positioned an adjusting screw 42. The sleeve 38 has an inwardly extending receiver 44 that extends into the radial arm bore 40. The receiver 44 has a threaded bore in which the adjusting screw 42 is threadedly secured. With this arrangement, upon rotation of screw 42 in one direction the sleeve 38 moves radially outwardly relative to the arm 36 and upon rotation of screw 42 in the opposite direction the sleeve 38 moves radially inwardly toward the body portion 30 as illustrated by the phantom lines in FIG- URE 2. Suitable seal means are provided between the inner walls of the sleeve member 38 and the external surfaces of arm 36 to prevent dirt, dust or other foreign material from entering the radial arm bore 40. Extending forwardly from the sleeve 38 are cutter element holders 46 land 48 that are suitably secured to the sleeve 38 by means of bolts 50. Cutter elements '52 are secured to the front edges of the cutter element holders 46 and 48 so that upon rotation of the boring heads annular kerfs are formed in the mine face, as indicated in FIGURE 2.

Each of the radially extending arms 36 has sleeves 38 secured thereto with the cutter element holders 46 and 48 extending forwardly therefrom. The sleeves 38 have the cutter element holders spaced at different radial distances from the axial center of the boring head and from the other cutter element holders 46 so that a plurality of annular kerfs of different diameters are formed in the mine face, as illustrated in FIGURE 2. Wedge type breakers 54 (FIGURE 1) are secured to the sleeves 38 and extend forwardly therefrom. The wedge type breakers 54 dislodge the annular cores of material remaining between the annular kerfs formed by the cutting elements 52 so that the boring heads each form a bore having a radius equal to the distance between the axial center of the boring head and the cutter elements 52 secured to the outer cutter element holder 46.

The boring heads 18 and 20 have an independently rotatable inner or center portion generally designated by the numeral 56 that has a circular plate-like body portion 58 with tool holders 60 and 62 extending forwardly therefrom. The tool holders 60 and 62 are secured to the body portion 58 by means of bolts 64. Extending axially from the inner portion of the boring head is a core burster 66 that is cylindrical in shape and has cutter elements 68 secured to the front end thereof. Cutter elements 70 are secured to the front edge of the tool holders 60and 62 so that upon rotation the cutter elements form an axial core and a coaxial annular kerf adjacent the axial center of the boring head. A wedge type breaker 72 (FIGURE 1) is secured to the center cutting element 56 and dislodges the annular kerf formed between the core burster and the cutter elements 68 and 70. The core formed by the cutter elements 68 is dislodged by means of a fixed wedge plate within the cylindrical core burster 66. The boring head inner portion has a rearwardly extending receiver 74 with a splined bore 76. A shaft 78 extends through the tubular portion 80 of the boring head outer portion 30 and extends rearwardly to the gear case 16. Bearings 82 are positioned between in the bore 80 and support the shaft 78' so that the shaft 78 with the cutting element 56 secured thereto is rotatable relative to the boring head outer portion 30. Within the outer member tubular portion 80 is an arm adjusting tubular shaft 84 to which a gear 86 is secured. The gear 86 meshes with a gear 90 secured to the end portion of radially extending shaft 42. Thus, by relative rotation of shaft 84 the threaded shaft 42 is rotated to radially adjust the sleeve 38 positioned on the radial arm 36.

The gearing arrangement to rotate the boring head central or inner portion 56 relative to the boring head outer portion 30 and to rotate the outer portion 30 is illustrated schematically in FIGURES 3 and 4. For convenience, the drive for one boring head will be described in detail. It should be understood, however, that the drive for the other boring head is similar and that the boring heads are tied to each other by gearing so that they rotate in opposite directions and in timed relation to each other.

Each boring head has an electric drive motor associated therewith. The drive motor has a shaft connected to a drive shaft 92 through suit-able clutching means. The shaft 92 is suitably supported within the gear case' 16 and has a drive gear 94 nonrotatably secured thereto. Thus, the rotation of the motor shaft is transmitted through the clutch mechanism to the shaft 92 to rotate gear 94. Gear 94 meshes wih an intermediate gear 96 suitably supported on a shaft 98. The gear 96 meshes with gear 94 to rotate shaft 98.

The shaft 98 has a front portion with gear teeth formed thereon which will hereinafter be referred to as gear 100. The gear 100 meshes with a gear 102 nonrotatably supported on shaft 104. Also positioned on shaft 104 rearwardly of gear 102 is a gear 106 that rotates with shaft 104. The front end of shaft 104 has gear teeth formed thereon and will be referred to as gear 108- Gear 106 nonrotatably secured to shaft 104 meshes with an intermediate idler gear 110 suitably supported within the gear case 16 (FIGURES 2 and 3). The gear 110 meshes with a gear 112 that is splined to the shaft 78. The shaft 78 extends forwardly through the tubular por tion 80 of the boring head outer portion 30 and is nonrotatably connected to the boring head inner portion 58. The gear 108 meshes with gear 114 that is nonrotatably secured to the shaft 26. The shaft 26 is connected to the boring head outer portion 38. With this arrangement the rotation of drive gear 94 in a counterclockwise direction, as indicated in FIGURE 4 and the right hand portion of FIGURE 3, rotates gear 96, shaft 98 and gear 180 in a clockwise direction. Gear 188 meshes with gear 102 and rotates shaft 184, gears 186 and 108 in a counterclockwise direction. Gear 106 meshes with idler gear 110 (FIGURE 3) to rotate gear 110 in a clockwise direction. Gear 112 meshes with gear 110 and rotates in a counterclockwise direction to drive the shaft 78 in a counterclockwise direction and thus rotate the boring head central portion 56 in a counterclockwise direction. The gear 114 meshes with the gear 108 on shaft 104 so that the gear 114 is driven in a clockwise direction by the counterclockwise rotation of gear 188. The gear 114 is connected to the shaft 26 which, in turn, is connected to the boring head outer portion 30 so that the boring head outer portion 30 with the radial arms 36 rotates in a clockwise direction. Thus, with gearing positioned within the gear case 16 rearwardly of the boring head radial arms 36, the boring head inner portion 56 is driven in a direction opposite to the boring head outer portion 30. The gearing for rotating the boring head inner portion 56 and outer portion 30 does not interfere with the retractability and extensibility of the sleeves 38 on the boring head radial arms 36.

The electric motor associated with the boring head 20 on the left side of FIGURE 3 rotates in a clockwise direction to thereby rotate the outer portion of boring head 20 in a direction opposite to the direction of rotation of the outer portion of boring head 18 as is indicated by the arrows in FIGURES 1 and 3. The gears 102 associated with boring heads 18 and 20 are in meshing relationship with each other so that the boring heads are maintained in proper phase relation to each other and rotate in timed relation to each other. The gearing previously described may be suitably arranged to provide the desired speed differential between the boring head outer portion 30 and the inner portion 56.

There is provided a gear 116 secured to the tubular shaft 84 by means of a spline arrangement (FIGURE 4). The gear 116 is nonrotatable relative to the shaft 84 and is movable axially on shaft 84 into an internally geared receiver 118 that forms a part of the shaft 26. When gear 116 is engaged within receiver 118, the sleeves 38 remain in a preselected fixed position on the radial arms 36 through the arrangement of gears 86 and 90 in FIGURE 2. When it is desired to adjust the sleeves 38 on the radial arms 36, the gear 116 is moved rearwardly and the shaft 84 is rotated relative to shaft 26 by a suitable drive mechanism 120 connected thereto through suitable gearing 122.

In FIGURE 5 there is schematically illustrated another species of the boring head having an inner portion that is rotatable relative to the outer portion. The boring head generally designated by the numeral 124 has an outer portion generally designated 126 and an inner portion generally designated 128. The outer portion 126 has a body portion 130 with a plurality of radially extending arms 132 with extensible and retractable sleeves 134 positioned thereon similar to the sleeves 38 on the boring head previously described. The outer portion 126 is substantially the same in construction as the outer portion 30 in the species of the invention illustrated in FIG- URE 2. The central portion 128 has a body portion 136 With a core burster 140 extending forwardly therefrom. The body portion 136 also has a plurality of radially extending arms 142 with cutting element holders 144 extending forwardly therefrom. The cutter element holders 144 are semicircular in shape, as illustrated in FIGURE 5, and have a circumferential dimension which is greater than the spacing between the radial sleeves on the outer member radial arms 132. Cutting elements extend forwardly from the core burster 140, the cutting element holders 144 and from cutting element holders 146 and 148 extending from the adjustable sleeves 134. The radial arms 132 are positioned in a plane that is spaced rearwardly of a plane formed by the radial arms 142 in a manner similar to the arms 36 illustrated in FIGURE 2. In an extended position the cutter element holders 146 on sleeves 134 clear the arms 142 to permit relative rotation of the inner and outer members 126 and 128. In a retracted position, however, there is insuflicient clearance for the cutter element holders 146 on sleeves 134. The inner and outer members 128 and 126 must be positioned as illustrated in FIGURE 5 to retract the sleeves 134.

Where it is desired to retract the sleeves 134 on arms 132 the boring head 124 is slowly rotated until the position illustrated in FIGURE 5 is attained. Then the sleeves 134- may be retracted between the cutter elements 144 on the radially extending arms 142 that form a part of the inner member 128, as is illustrated in FIGURE 5. With this arrangement it is now possible to position a greater number of cutting elements between the core burster and the outer cutter elements and to rotate these intermediate cutter elements at speeds which produce optimum efficiency of all of the cutter elements on the boring head. The sleeves 134 on the outer radial arms 132 may be retracted between the cutting elements 144. The inner and outer portions 128 and 126 may be driven by gearing similar to the gearing illustrated in FIGURES 3 and 4 and previously described. The sleeves 134 are indicated in FIGURE 5 in their extended position by phantom lines.

According to the provisions of the patent statutes, the principle, preferred construction and mode of operation of the invention have been explained and what is considered to represent its best embodiments have been illustrated and described. It should be understood, however, that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a boring type continuous mining machine the combination comprising,

a frame member supporting drive means for a plurality of boring heads,

a drive gear housing supported on the front portion of said frame member,

a plurality of boring heads extending forwardly from said drive gear housing,

said boring heads each having an outer portion and an inner central portion, said inner central portion arranged coaxially with said outer portion, said inner and outer portions being rotatable relative to each other,

said outer portion having arm members extending radially therefrom,

sleeve members positioned on said arm members, said sleeve members being adjustable radially on said arm members, said sleeve members having cutting elements extending forwardly therefrom and arranged to cut annular kerfs,

said inner central portion having cutting elements ex- 4 tending forwardly therefrom arranged to cut annular kerfs concentric with said kerfs cut by said cutting elements on said outer portion sleeve members, said outer portion connected to a tubular shaft extending rearwardly into said drive gear housing the portion of said tubular shaft positioned within said drive gear housing having an external gear thereon,

said inner central portion connected to a shaft member extending rearwardly through said tubular shaft into said drive gear housing, said shaft member having a gear member secured thereto, and

driving connections including gear means within said drive gear housing connecting said drive means to said gear on said tubular shaft and to said gear on said shaft member, said gear means arranged to rotate said boring head inner central portion and outer portion in opposite directions at different angular velocities.

2, In a boring type continuous mining machine the combination comprising,

a frame member supporting drive means for a plurality of boring heads,

a drive gear housing supported on the front portion of said frame member,

a plurality of boring heads supported by and extending forwardly from said drive gear housing,

said boring heads each having an outer portion and an inner central portion, said inner central portion arranged coaxially with said outer portion, said inner central portion and said outer portion being rotatable relative to each other, said outer portion having a tubular body portion with a plurality of arms extending radially therefrom, said arms having an elongated radial chamber therein opening into said tubuiar body portion,

sleeve members slidably positioned on said arm members, said sleeve members having cutting elements extending forwardly therefrom and arranged to cut annular kerfs in a vertical face of material,

adjusting means positioned in said chambers and connected to said respective sleeve members, said ad justing means operable to radially adjust the position of said sleeve members on said arm members, said adjusting means having portions extending into said tubular body portion,

said inner central portion having other cutting elements extending forwardly there-from, said other cutting elements arranged to cut concentric kerfs in said vertical face of material, said last named concentric kerfs having a diameter smaller than the diameter of said kerfs cut by said cutting elements on said sleeve members,

said tubular body portion connected to a tubular shaft extending rearwardly into said drive gear housing, the portion of said tubular shaft positioned within said drive gear housing having a first gear member thereon,

said inner central portion rotatably supported within said tubular body portion,

a shaft member coaxially positioned within said tubular body portion and secured at one end to said inner central portion, said shaft member extending rearwardly through said tubular body portion and said tubular shaft into said drive gear housing,

the portion of said shaft positioned within said drive gear housing having a second gear member thereon, and

driving connections including constantly meshing gearing within said drive gear housing connecting said drive means to said first gear on said tubular shaft and to said second gear on said shaft member so that said drive means rotates said boring head inner central portion and said outer portion in opposite directions at different angular velocities.

3. In a boring type continuous mining machine as set forth in claim 2 in which said driving connections include a second shaft having a pair of gears secured thereto and rotatable therewith, one of said pair of gears meshing with said first gear on said tubular shaft, and

a third shaft having an idler gear secured thereto and rotatable therewith,

said idler gear meshing with said other gear of said pair of gears on said second shaft and with said second gear member on said shaft connected to said inner central portion.

4. In a boring type continuous mining machine as set forth in claim 2 which includes,

a second tubular shaft coaxially positioned on said shaft member connected to said inner central portion,

said second tubular shaft positioned within said body portion tubular portion and extending rearwardly within said first tubular shaft into said drive gear housing,

said second tubular shaft connected to said adjusting means extending into said tubular body portion, said second tubular shaft arranged upon rotation relative to said body portion to move said sleeve members radially on said arm members, and

means within said drive gear housing to connect said second tubular shaft to said first tubular shaft so that said sleeve members maintain a fixed radial position on said arm members 5. In a boring type continuous mining machine the combination comprising,

a frame member supporting drive means for a plurality of boring heads,

a drive gear housing supported on the front portion of said frame member,

a plurality of boring heads supported by and extending forwardly from said drive gear housing,

said boring heads each having an outer portion and an inner central portion, said inner central portion arranged coaxially with said outer portion, said inner central portion and said outer portion being rotatable relative to each other, said outer portion having a tubular body portion with a plurality of arms extending radially therefrom, said arms having an elongated radial chamber therein opening into said tubular body portion,

sleeve members slidably positioned on said arm members, said sleeve members having cutting elements extending forwardly therefrom and arranged to cut annular kerfs in a vertical face of material,

adjusting means positioned in said chambers and connected to said respective sleeve members, said adjusting means operable to radially adjust the position of said sleeve members on said arm members, said adjusting means having portions extending into said tubular body portion,

said inner central portion having other cutting elements extending forwardly therefrom, said other cutting elements arranged to cut concentric kerfs in said vertical face of material, said last named concentric kerfs having a diameter smaller than the diameter of said kerfs cut by said cutting elements on said sleeve members,

said tubular body portion connected to a tubular shaft extending rearwardly into said drive gear housing, the portion of said tubular shaft positioned within said drive gear housing having a first gear member thereon,

said inner central portion rotatably supported Within said tubular body portion,

a shaft member coaxially positioned within said tubular body portion and secured at one end to said inner central portion, said shaft member extending rearwardly through said tubular body portion and said tubular shaft into said drive gear housing,

the portion of said shaft positioned within said drive gear housing having a second gear member thereon,

a second tubular shaft coaxially positioned on said shaft member connected to said inner central portion,

said second tubular shaft positioned within said tubular body portion and extending rearwardly within said first tubular shaft into said drive gear housing,

said second tubular shaft connected to said adjusting means extending into said tubular body portion, said second tubular shaft arranged upon rotation relative to said body portion to move said sleeve members radially on said arm members,

means within said drive gear housing to connect said second tubular shaft to said first tubular shaft so that said sleeve members maintain a fixed radial position on said arm members,

a second shaft positioned within said drive gear housing and having a pair of gears secured thereto and rotatable therewith,

one of said pair of gears meshing with said first gear on said tubular shaft,

a third shaft positioned within said drive gear housing and having an idler gear secured thereto and rotatable therewith,

said idler gear meshing with said other gear of said pair of gears on said second shaft and with said second gear on said shaft connected to said inner central portion, and

driving connections within said drive gear housing connecting said drive means to said second shaft so that upon rotation of said second shaft said boring head inner central portion and said outer portion rotate in opposite directions and at different angular velocities.

6. In a continuous mining machine operable to form a plurality of contiguous overlapping bores in a vertical face, the combination comprising,

a frame member supporting a plurality of drive motors,

a drive gear housing supported on the front portion of said frame member,

a plurality of boring heads supported by and extending forwardly from said drive gear housing, said boring heads operable to rotate in opposite directions in timed relation to each other,

said boring heads each having an outer portion and an inner central portion, said inner central portion arranged coaxially with said outer portion, said inner central portion and said outer portion being rotatable relative to each other, said outer portion having a tubular body portion with a plurality of arms extending radially therefrom, said arms having an elongated radial chamber therein opening into said tubular body portion,

sleeve members slidably positioned on said arm members, said sleeve members having cutting elements extending forwardly therefrom and arranged to cut annular kerfs in a vertical face of material,

adjusting means positioned in said chambers and connected to said respective sleeve members, said adjusting means operable to radially adjust the position of said sleeve members on said arm members, said adjusting means having portions extending into said body portion tubular portion,

said inner central portion having other cutting elements extending forwardly therefrom, said other cutting elements arranged to cut concentric kerfs in said vertical face of material, said last named concentric kerfs having a diameter smaller than the diameter of said kerfs cut by said cutting elements on said sleeve members,

said tubular body portion connected to a tubular shaft extending rearwardly into said drive gear housing, the portion of said tubular shaft positioned within said drive gear housing having a first gear member thereon,

said inner central portion rotatably supported within said tubular body portion,

a shaft member coaxially positioned within said tubular body portion and secured at one end to said inner central portion, said shaft member extending rearwardly through said tubular body portion and said tubular shaft into said drive gear housing,

the portion of said shaft positioned within said drive gear housing having a second gear member thereon,

a second tubular shaft coaxially positioned on said shaft member connected to said inner central portion,

said second tubular shaft positioned within said body portion tubular portion and extending rearwardly within said first tubular shaft into said drive gear housing,

said second tubular shaft connected to said adjusting means extending into said tubular body portion, said second tubular shaft arranged upon rotation relative to said body portion to move said sleeve members radially on said arm members,

means within said drive gear housing to connect said second tubular shaft to said first tubular shaft so that said sleeve members maintain a fixed radial position on said ar-m members,

each of said boring heads having a second shaft positioned within said drive gear housing in spaced parallel relation to each other, said second shaft having three gears secured thereto and rotatable therewith,

one of said three gears meshing with said first gear on said tubular shaft,

each of said boring heads having a third shaft positioned within said drive gear housing and having an idler gear secured thereto and rotatable therewith, said idler gear meshing with another of said three gears on said second shaft and with said second gear on said shaft connected to said inner central portion, said third gear on each of said second shafts meshing with each other so that said second shafts rotate in timed relation with each other, and

driving connections within said drive gear housing connecting said respective drive motor to said respective second shaft associated with each boring head so that upon rotation of said second shafts said boring heads rotate in opposite directions to each other and said respective boring head inner central portions and said outer portions rotate in opposite directions and at different angular velocities.

7. In a boring type continuous mining machine the combination comprising a frame member supporting drive means for a plurality of boring heads,

a drive gear housing supported on the front portion of said frame member,

a plurality of boring heads extending forwardly from said drive gear housing,

said boring heads each having an outer portion and an inner central portion,

said inner portion arranged coaxially with said outer portion,

said outer portion having arm members extending radially therefrom,

sleeve members positioned on said arm members, said sleeve members being adjustable radially on said arm members and having an inner edge portion spaced radially from said outer portion, said sleeve members having cutting element holders extending forwardly therefrom,

said inner central portion having arm members extending radially therefrom in a plane spaced forwardly from the plane of said arm members on said outer portion,

semicircular cutting element holders extending forwardly from said inner central portion arm members,

said cutter element holders on said sleeve members extending forwardly into the plane formed by said inner central portion arm members,

said inner central portion arm members having a radial dimension greater than the radial dimension of said sleeve member inner edge portions from said outer portion in a sleeve member retracted position and a radial dimension less than the radial dimension of said sleeve member inner edge portion from said outer portion in a sleeve member extended position,

said outer portion connected to a tubular shaft extending rearwardly into said drive gear housing, the

portion of said tubular shaft positioned Within said drive gear housing having an external gear thereon,

said inner central portion connected to a shaft member extending'rearwardly through said tubular shaft into said drive gear housing, said shaft member having a gear member secured thereto, and

driving connections including gear means Within said drive gear housing connecting said drive means to said gear on said tubular shaft and to said gear on said' shaft member, said gear means arranged to rotate said boring head inner central portion and outer portion in opposite directions at difierent angular velocities.

References Cited by the Examiner ERNEST R.

UNITED STATES PATENTS Hughes 29960 X McKinley 29959 X Alspaugh et a1. 2996O X Poundstone 29961 X Thassey et a1 2998O X PURSER, Primal Examiner. 

1. IN A BORING TYPE CONTINUOUS MINING MACHINE THE COMBINATION COMPRISING, A FRAME MEMBER SUPPORTING DRIVE MEANS FOR A PLURALITY OF BORING HEADS, A DRIVE GEAR HOUSING SUPPORTED ON THE FRONT PORTION OF SAID FRAME MEMBER, A PLURALITY OF BORING HEADS EXTENDING FORWARDLY FROM SAID DRIVE GEAR HOUSING, SAID BORING HEADS EACH HAVING AN OUTER PORTION AND AN INNER CENTRAL PORTION, SAID INNER CENTRAL PORTION ARRANGED COAXIALLY WITH SAID OUTER PORTION, SAID INNER AND OUTER PORTIONS BEING ROTATABLE RELATIVE TO EACH OTHER, SAID OUTER PORTION HAVING ARM MEMBERS EXTENDING RADIALLY THEREFROM, SLEEVE MEMBERS POSITIONED ON SAID ARM MEMBERS, SAID SLEEVE MEMBERS BEING ADJUSTABLE RADIALLY ON SAID ARM MEMBERS, SAID SLEEVE MEMBERS HAVING CUTTING ELEMENTS EXTENDING FORWARDLY THEREFROM AND ARRANGED TO CUT ANNULAR KERFS, SAID INNER CENTRAL PORTION HAVING CUTTING ELEMENTS EXTENDING FORWARDLY THEREFROM ARRANGED TO CUT ANNULAR KERFS CONCENTRIC WITH SAID KERFS CUT BY SAID CUTTING ELEMENTS ON SAID OUTER PORTION SLEEVE MEMBERS, 